Each person on a team brings a unique perspective to the process; i.e., how things work; what happens when changes are made, and how to sustain improvements during daily work. Contributions are made from each individual's skill set and the team's synthesis of ideas.
Division of labor is the economic term for the practice of assigning small parts of a complicated job to individual workers who specialize in doing just their small part.
This division of labor into small, specific tasks and the assignment of employees to do a single task is called specialization. The rationale for specialization is efficiency: It minimizes the time lost when workers shift from one task to another, and it facilitates training.